In wiper devices that wipe the glass of a windshield or the like in an automobile, as illustrated in FIG. 19A, a wiper motor moves wiper arms 150D, 150P back and forth between lower return positions P4D, P4P and upper return positions P3D, P3P. Wiper blades 154D, 154P are coupled to leading end portions of the wiper arms 150D, 150P. The movement of the wiper arms 150D, 150P most often forms substantially circular arc shaped trajectories centered on pivot shafts 152D, 152P of the respective wiper arms 150P, 150D. Wiping ranges 156D, 156P, these being regions of a windshield glass 1 or the like that are wiped by the wiper blades 154D, 154P, accordingly have substantially fan shapes centered on the pivot shafts 152D, 152P.
It is necessary for wiper devices to prioritize wiping of the windshield glass 1 on the side of a driver's seat in order to secure the driver's field of view. Moreover, the windshield glass 1 of an automobile is substantially in the shape of an isosceles trapezoid. Therefore, in a parallel (tandem) wiper device in which the two wiper arms 150D, 150P swing at the same time and in the same direction as each other, in cases in which the pivot shafts 152D, 152P are provided below the windshield glass 1, the upper return position P3D of the wiper blade 154D on the driver's seat side is provided at a position alongside and close to a driver's seat side edge 1A of the isosceles trapezoid shaped windshield glass 1 (one upright side of the isosceles trapezoid shape).
In order to prioritize wiping of the driver's seat side of the windshield glass 1, in a tandem wiper device, the upper return position P3P of the wiper blade 154P on the front passenger seat side is also provided alongside the driver's seat side edge 1B of the windshield glass 1. However, as described above, since the wiping range of the wiper blade 154P is substantially fan shaped, providing the upper return position P3P at the position described above results in a non-wiped region 158 that is not wiped by the wiper blade 154P, centered on an upper corner 1C on the front passenger seat side of the windshield glass 1.
As illustrated in FIG. 19B, the implications of the non-wiped region 158 are particularly serious when turning left at a crossroad or the like, as it is possible that the driver's awareness of pedestrians may be impeded.
Japanese Patent Application Laid-Open (JP-A) No. 2000-25578 discloses a wiper device in which a front passenger seat side wiper blade is operated in a manner capable of wiping the non-wiped region 158.